Mercury vapor rectifier tube employing magnetic field



Nov 24, ln953 J, H, COLEMAN 2,660,687

MERCURY VAPOR RECTIF'IER TUBE EMPLOYING 'MAGNETIC FIELD Filed 0G17. 50,1952 fly-1 y x x L t @i 5 ff IN/ENTOR.

Im-INH. EDLE-Mam A' ORNEY Patented Nov. 24, 1953 UNITED STAT PATENTOFFICE MERCURY VAPOR RECTIF-IER-TUBE EMPLOYIlNllGrv MAGNETIC. yFIELDJohn HL- Coleman,A West Palm Beach; Fla., as'- sig'nor to RadioCorporationrof America, arcor-- pnrationofcelaware Application October30, 1952, Serial No. 317,709 6i claims.4 (o1. S13- 161)v type ofdischarge device thathasalow. voltageA drop on the l*forward portion of:thecycle andan extremely highA inversefvoltageto prevent arc back..

This` invention also is specifically designed'V to` eliminate the slowswitchinglimitations vof mer.

cu-ry vapor type-of rectifier device: so that the device may be used atmuchhigher frequencies; ItV is therefore an obj ect of? this-inventionto provide a nevvy and improved `mercury vapor type of dischargey deviceutilizing: a magnetic field for electron trapping.

Another objectief Sthis inventionis to provide amercury vvapor rectiertuberforvhighefrequency,

high-voltage. operation thatl will. have`V a high.

inverse. voltage rating.r

Aiurther object ofthis invention isftoprovide.`

ak novel mercury. vapor rectiier tube-utilizing:I an

appledtmagnetici field and employing; electron. trappingito. aid `intheswitching ofi an arczitype;

discharge.;

A still '.furthern obj ect: ofi thisf:` invention.: is toz` provide a:new andi: novel mercuryzvapor; type:

discharges devicez that.`-` utilizes-v anarc1type1 dis.-V charge. thatmay'berapidly Vswitched on: and4 off x These andother objectstare`rattained nrac:

cordance 1 with theigeneral aspect` of. this inven-v tion .by'provi-ding. 1a .mercury `Vapor discharge de.-

vice comprising:V a. pair of:.spaced; apart cathodeV plates,r onenormally-being in. contact.v with a. mercuryipool, and thel othersupportingranfelongated gniter rod.v Surrounding the. elongated rod isagring shaped anode.- During operation, a magnetic iield isapplied'parallel'to the elongated rodvfor the purpose of trapping theelec Thev electron .trapping-f, caused by the magnetic fieldand theelectrode potentials,- causes :a-large nunk trons between they rod and]Fthe anode.

ber of mercury vapor-positive ionsv to be; formed so that a glowdischarge occursvbetween-therod and anode. which in'imediately;v istransformed Z Figure lisa cross sectional View of an Vembodiment ofthisinvention utilizing. an ion accelerating. gradient that it establishedtoward the mercury pool;

Figure-21s' a cross sectional view ofanother embodiment of .thisinvention.

Referring now toiFigure l, there is` shown a crcssesectional view of oneembodimentcf this invention. Included' in this'view is a gastightenclosure which. utilizes; the; elements of V the' structure; as shown;toformthe gas tight eni closure; The enclosureincludesa pair'ofv subestantially parallel spaced" apart cathode disks; I 5l and I1. Separatingthese' twol cathodedisks'; is aY hollowtubularinsulatingV member I4;Inside theenclosuraand normallyon cathode disk Il ConnectedY tocathodeidi'skv is a mercury pool. I t.

l5' is' an elongated/fred; origniter electrode; IB

Substantially parallel tothe' twoy cathode disks I5 and y i'I'f is fan'A annular anode I I supported-hyported inV a recessedp'ortion- I3 ofthe 'insulating member I las shown.

The'cathode1-dislrs i5`a-nd- I1 are sealedtothei insulatingmernber It;as fisf the recessed portion I3, to form a gas ytight seal so thatmercury vapor will-not escape fromftheenclosure. The Yconductive-supportrodiI2isfseailecl4 inthe same mannerv toftliereeessed" insulatingmemberv I3 asf shown. Anyof'tliewel-l known sea1smay=beutilizedto form`the-junctions betweenthe various members; Disks: I5f" and I1'I' areyconstructed of magnetic material such as- Kovar. The l insulatingv mem-Y bers I3- andl maybe-'constructed of "glassi The elements- I I, I2.;andv`l IIl are preferably substantially non-magnetic topreventdistortion.` of a` magnetic eld'.' Adjacent the cathode disksor platesfvI5 and'l'liis a magnet I Bihaving a magnetic held* substantially: in--the direction as is indicated by the arrow and letter H. ItV should` beunderstood that a circular type magnetmay also beusedhcwever;` itisrdesiredf to havethe magnetic lines offlux pass Vthrough anode I Isubstantially parallel te the igniter rod I6 vas is shovvnf.v

Al recess portionv I3; ininsulating member. I4, is for. thepurposepo`eliminating sputtering of the mercury onto the insulating member I4 andthus .to maintainthehigh voltage characteristics of the device. Thelead-in wire, or rod, |12 lshould be rigidenoughtc support theanode. I Iwithout permitting itto bend so as tov touch the igniter electrode It,or the mercury pool I8. It should be noted that ligniter velectrode I6extends below the anode II. This extension should' be. far enough sothat theelectric field of the gniter electrode I6 appears'to beinnitelylongwhen viewed by the anode II. In order to do this the igniterelectrode I6 must extend below the anode iI a distance approximatelyequal to the radius of the anode II.

In operation of this embodiment of my invention, a potential differenceis applied between the igniter I6 and the anode II. The potentialdifference causes electrons to be emitted 'from igniter I6 in adirection toward anode II. Due to the magnetic field the electrons willtravel in a curvilinear path and will thus produce a sufficient numberof positive ions to cause a glow discharge to occur between these twoelectrodes. This phenomena is explained more completely in a copendingapplication of mine Serial Number 93,324, filed May 14, 1949, now PatentNumber 2,615,139. When the current through the tube from the glowdischarge is of suicient value, an arc discharge forms between themercury pool E 8 and the anode I I, resulting in a discharge that has alov.7 arc drop and a very high current rating.

The rate at which the arc discharge occurs can be made to be consistent,as well as fast, if the part of the cathode formed by cathode disk I andigniter I3 is elevated slightly in potential above the portion of thecathode formed by cathode disk I1 and mercury pool I8. This occurs dueto the deflection of a large portion of the positive ions, that areformed in the glow discharge, down to bombard the mercury pool I8. Thepotential adjustment between these elements is accomplished by means ofa resistor 2S connected between the cathode disk I5 and cathode disk I1as shown.

When the voltage is reversed, i. e. the inverse cycle for rectication,the arc is extinguished as electrode II is now negative with respect tothe cathode disks I5 and I1, the igniter electrode I6, and the mercurypool I8. Because there is no electron trapping in the inverse portion ofa cycley i. e. when anode I I and rod I2 are negative with respect tothe other electrodes, no glow discharge will occur. When the anodeswings positive again, on the forward portion of the cycle, electrontrapping again results and the process is repeated.

Referring now to Figure 2, there is a crosssectional view of anembodiment of this invention wherein an anode 2| is a washer shapedanode extending between the hollow tubular insulating members 24 and 30.Cathode disks 25 and 21 each have shielding members 22 inside theenclosure. The shielding members 22 are cylindrical and will normallycontain the mercury pool 28. The purpose of these shielding members 22is to prevent sputtering on the insulating members 24 and 30, and alsoto protect the glassto-metal seals between insulating members 24 and 30and cathode disk 21 from harmful eiects of the mercury.

Since anode 2l extends through the enclosure it is especially welladapted for cooling. This is true because the outer circumference ofanode EI is exterior the enclosure and, if desired, fins or other wellknown cooling coniigurations may be placed on the outer circumference ofthe anode 2|.

The other elements of Figure 2 are similar to those shown in Figure 1,as is the operation of the device, and further explanation of theseelements or of the operation is not deemed necessary.

I claim:

l. A mercury vapor discharge device, comprising a gas tight enclosure,said enclosure comprising a pair of spaced apart cathode disks andinsulating means intermediate the periphery of said disks, sealing meansjoining the ends of said disks and said insulating means in gas tightrelation, a mercury pool within said enclosure and normally in contactwith one of said disks, an elongated rod connected to the other of saiddisks and extending toward said mercury pool, said rod and said mercurypool normally being spaced apart, a ring shaped anode within saidenclosure and spaced around said rod, conductive means supporting saidanode and extending through said insulating means, and magnetic meansadjacent said enclosure for applying a magnetic eld parallel to saidrod.

2. A mercury vapor discharge device, comprising a gas tight enclosure,said enclosure comprising a pair of spaced apart cathode disks andinsulating means intermediate the periphery of said disks, sealing meansjoining said insulating means and said disks in gas tight relation, amercury pool within said enclosure and normally being in contact withone of said disks, an elongated rod connected to the other of said disksand extending toward said mercury pool but normally being spacedtherefrom, a ring shaped anode within said enclosure and spaced aroundsaid rod, a conductive rod connected to said anode and extending throughsaid insulating means, and a magnet means adjacent said disks exteriorsaid enclosure and so positioned with respect to said elements that theeld of said magnet extends through said anode substantially parallel tosaid rod.

3. A mercury vapor discharge device, comprising a gas tight enclosure,said enclosure comprising a pair of spaced apart cathode disks and apair of spaced apart hollow tubular insulating members intermediate theperiphery of said disks, an anode plate extending between saidinsulating members on all sides and having a substantially roundaperture therein, sealing means joining said insulating members to theperiphery of said cathode disks and to said anode plate in gas tightrelation, shielding means connected to said disks and extending towardsaid anode but spaced therefrom, a mercury pool within said enclosureand normally in contact with one of said disks and within said shieldingmeans, an elongated rod extending from the other of said cathode disksthrough said aperture toward said cathode pool, said rod normally beingspaced from said anode and said mercury pool, and a magnet having onepole adjacent each of said disks exterior said enclosure and sopositioned with respect to said elements that the eld of said magnetextends through said anode substantially parallel to said rod.

4. A mercury vapor discharge device, comprising a gas tight enclosure,said enclosure comprising a pair of spaced apart cathode disks andinsulating means intermediate the periphery of said disks, saidinsulating means including a recessed portion, means joining saidinsulating means and said disks in gas tight relation, a mercury poolwithin said enclosure and normally being in contact with one of saiddisks, an elongated rod connected to the other of said disks andextending toward said mercury pool but spaced therefrom, a ring shapedanode within said enclosure and spaced around said rod, a conductive rodextending from said anode through said recessed portion, and a magnethaving one pole adjacent each of said disks and so positioned withrespect to said elements that the eld of 5 said magnet extends throughsaid anode substantially parallel to said rod.

5. A mercury vapor discharge device, comprising a gas tight enclosure, apair of spaced apart cathode disks each having one surface within saidenclosure, means to support said disks in spaced apart relationship, amercury pool normally being in contact with one of said disks, anannular anode supported parallel to said disks intermediate thereof, anelongated igniter rod connected to the other of said disks and extendingtoward said mercury pool 'but spaced therefrom and through said annularanode, and means to apply a magnetic eld to said device so that saidmagnetic eld passes through said anode substantially parallel to saidigniter rod.

6. A mercury vapor discharge device, comprising a gas tight enclosure,said enclosure com prising ra pair of spaced apart cathode disks andinsulating means intermediate the periphery of said disks, sealing meansjoining the ends of said disks and said insulating means in gas tightrelation, a mercury pool Within said enclosure and normally in contactwith one of said disks, an annular shaped anode within said enclosureintermediate said disks and substantially parallel thereto, means tosupport said anode extending through said insulating means and sealedthereto, an elongated rod connected to the other of said disks andextending through said anode toward said mercury pool but spacedtherefrom, said rod being spaced Within said anode and extending throughsaid anode a distance substantially equal to the radius of said anode,and means to apply a magnetic eld to said device so that said magneticfield will be substantially parallel to said elongated rod.

JOI-IN I-I. COLEMAN.

No references cited.

